1. Field of the Invention
The present invention relates to an image taking system and a lens apparatus that have a ranging function.
2. Description of the Related Art
In conventional television live broadcast such as marathon live broadcast, for example, a distance between a first place runner and a second place runner is often announced. The distance between the runners at this time is roughly measured by an announcer or a reporter by sight, or calculated based on a period of time from a time when the first place runner passes a certain point until a time when the second place runner passes the point and running speeds of the runners. Therefore, the distance between the runners announced by the announcer or the like is not accurate. Further, the viewer cannot visually perceive the distance only by the announcer or the like vocally announcing the distance to the viewer.
Japanese Patent Application Laid-Open No. 2003-329915 discloses the following image taking system. First, manual focus is performed on a first object, and a distance to the first object is calculated based on an in-focus position of a focus lens. Subsequently, manual focus is performed on a second object in the same manner as described above, and a distance to the second object is calculated based on an in-focus position of the focus lens. Then, a difference between the calculated distances to the first and second objects is determined, and information on the difference is displayed as being superimposed on an image signal.
Japanese Patent Application Laid-Open No. 2001-124544 discloses the following ranging apparatus. An object is irradiated with ranging light, and its reflected light is received by a charge coupled device (CCD), to thereby detect a distance to the object corresponding to each pixel based on an amount of the received light. Such a ranging apparatus is a so-called active multi-point ranging apparatus. A touch panel is disposed in a display device for displaying a taken image, and a pointing pen is used for selecting a pixel corresponding to a measurement point. Alternatively, a direction indication button is provided to the apparatus, with which a cursor on a screen is controlled, to thereby select a pixel corresponding to a measurement point. Then, a distance corresponding to the selected pixel is displayed on the screen.
With the ranging apparatus disclosed in Japanese Patent Application Laid-Open No. 2001-124544, distances to multiple objects may be calculated and displayed without performing the focus operation as in the system disclosed in Japanese Patent Application Laid-Open No. 2003-329915.
However, in the case of the ranging apparatus disclosed in Japanese Patent Application Laid-Open No. 2001-124544, in a style of taking a moving image in the marathon live broadcast or the like, a person taking the image needs to use the pointing pen or operate the direction indication button to designate a measurement point while taking the moving image, which complicates the operation of the person taking the image.
Further, when the person taking the image performs panning (hereinafter, referred to as “pan”) and tilting (hereinafter, referred to as “tilt”) operations or a zoom operation after designating the measurement point, the person taking the image needs to select a measurement point again because the designated measurement point deviates from the intended object. Particularly in such a case as the marathon live broadcast where the person taking the image wishes to select multiple measurement points, the above-mentioned complicated operation may be highly burdensome to the person taking the image.